The present invention relates to an electric rotary machine in which a rotor winding is provided with an air gap pick-up type cooling structure.
For example, as disclosed in page 151 of "MANUFACTURING AND MAINTENANCE OF ELECTRIC MACHINE COIL" by H. Sequenz, issued by DEVELOPMENT COMPANY on Jan. 1, 1990, in this cooling structure, a plurality of plate-shaped conductors forming a winding conductor each have a plurality of through holes perforated therein and a plurality of V-shaped flow paths each permitting cooling gas to flow in the axial direction of the rotor core while allowing the cooling gas to flow in the radial direction are formed in the winding conductor.
However, an electric rotary machine employing the above-mentioned cooling structure could not increase a quantity of cooling gas flowing in the cooling gas flow paths even if a thermal load was increased according to increase of output. Therefore, the cooling performance could not be improved and output could not be increased. This reason is that dynamic pressure occurring on the entry side of the cooling gas flow paths and negative pressure occurring on the exhaust side are determined fixedly by an outer diameter and rotation numbers of the rotor. That is, the outer diameter of the rotor, in the case of two poles, is limited to about 1 m because of restriction on material strength thereof, and the revolution number is determined 3000 rpm or 3600 rpm.
Further, in an electric generator employing the above-mentioned cooling structure, heat transfer of the cooling gas could not be increased and the cooling performance could not be improved even if flow of the cooling gas was disturbed by making the inner side of the cooling gas flow paths concave and convex. This reason is that the temperature of cooling gas increases according to increase in flow resistance of the cooling gas and an increment of the heat transfer of the cooling gas is canceled with the temperature increase. Although it was desirable to increase a quantity of cooling gas, it could not be increased for the above-mentioned reasons.